xii INTRODUCTION. . 



and third after the later pliocene. This last upheaval is supposed to be 

 still in progress. 



After the volcanic epoch came the glacial epoch, in which glaciers, far 

 grander than any that now exist in the Alps, were found in all the large 

 ravines on the high mountains, where their marks still remain, though 

 the rivers of ice gradually disappeared before the gradually increasing 

 warmth of the climate. The auriferous gravel in the ancient river-oeds 

 was deposited in the later pliocene, and it was followed by a great out- 

 break of volcanic energy, which covered the gravel with beds of lava and 

 other eruptive material. 



The gold deposits of the State lie not in the silurian rocks, which were 

 previou"sly considered to be the basis of all rich auriferous regions, but in 

 the Jurassic or triassic lithological formations of later date. 



The coal region of California lies not in the tertiary rocks, as was pre- 

 viously supposed, but in the cretaceous, the highest portion of the sec- 

 ondary era. 



The limits of the Jurassic and cretaceous have been traced with toler- 

 able accuracy over most of the area of the State. 



All the principal high points of the State, long known, have been as- 

 cended, their geological character examined, and their precise altitude 

 ascertained. 



A large district, previously unheard of by the public, has been found 

 to rise to a height of eleven thousand feet or more, with a hundred peaks 

 that rise about thirteen thousand feet, and a general elevation, extent, and 

 grandeur of scenery, that surpass those of Switzerland. 



The Big Tree has been found to exist, not merely in a few isolated 

 groves, as was supposed, but in extensive forests, with tens of thousands 

 of trees, along a considerable portion of the Sierra Nevada. 



Large bodies of excellent pasturage were found in places previously un- 

 known to the whites. 



An extensive collection of minerals, vegetables, and preserved or stuffed 

 animals, has been obtained, and will be prepared for exhibition so soon as 

 the State prepares a proper place for it. 



§ 6. Wheat — Within the last three years much larger crops of wheat 

 have been grown than ever before, and during 1867, San Francisco ex- 

 ported wheat and flour equivalent to 600,000,000 pounds of grain, the sale 

 price here being $12,600,000. The production of barley is about the same 

 as it was seven years ago, while tlie area sown in wheat has increased 



